In recent years, along with a sudden spread of smart terminals, a broadband high-speed communication scheme such as LTE (Long Term Evolution) and WIBRO (Wireless Broadband) has been adopted as standard, and an environment to detect an OFDM communication system using a cognitive radio technique happens to be the trend.
In general, how to identify the signals in an OFDM system is achieved by a method for estimating a frequency offset. In connection with the method for estimating a frequency offset, Korean laid-open Patent Application No. 2012-0048362, published on May 15, 2012, discloses a method to calculate the template and the correlation value of the sample of the pilot index located in the symbol and determine the frequency offset.
However, the method to identify the signals in the OFDM system is dependent on the presence of CP (Cyclic Prefix); and therefore there occurs a deviation in magnitude and position of peak value when the pilot signal exists. Further, In addition, the cycle analysis used to interpret the OFDM signal exhibits behavior that significantly changes in the cyclic frequencies depending on the size that the input signal is divided into frames.